Evolution in a lab flask: scientists witness virus speciating into two distinct species

One of the backbone’s of Charles Darwin’s Theory of Evolution is speciation — the branching of a species into two incipient species. Indirect evidence like genome analysis, fossils or plant and animal population surveys support speciation. However, the process is very slow requiring many breeding cycles, prompting some to question evolution. ‘How can a fish turn into an ape?! Prove it!” is a rhetorical question I often see on facebook and forums across the web. Well, here’s something to show them: a virus speciating in a lab flash, all under the watchful eye of researchers at University of California San Diego.

Justin Meyer, an assistant professor of biology at UC San Diego and lead author of the new study, began his experiments while still a doctoral student at Michigan State University. He and colleagues started breeding a “bacteriophage lambda”, which is a virus capable of infecting E. coli bacteria using two receptors. These are molecules that line the outside walls of the cell which, like holes for grappling, are used by the virus to attach itself to the infected cell.

What the researchers did was introduce two different types of bacteria to the virus, each with its different kinds of receptors. It didn’t take too long for the virus to branch into two distinct species, each specialized to handle the different cell receptors, as reported in the paper.

Molecular models of the two receptors the virus evolved to specialize on. Credit: Justin Meyer, UC San Diego

“The virus we started the experiment with, the one with the nondiscriminatory appetite, went extinct. During the process of speciation, it was replaced by its more evolved descendants with a more refined palette,” explained Meyer.

Per Darwin’s natural selection, the ‘jack-of-all-trades virus’ went extinct and only those individuals that specialized in attacking the new cell types passed on their genes. “The survival of the fittest led to the emergence of two new specialized viruses,” Meyer explained.

“With these experiments, no one can doubt whether speciation occurs,” Meyer added. “More importantly, we now have an experimental system to test many previously untestable ideas about the process.”

It’s worth mentioning that this isn’t the first time speciation has been observed in real time. For instance, scientists proved speciation occurs in fruit flies, which are far more complex organisms than viruses. If you’d like to learn more about speciation and the various case studies that prove it, check this link.